d8b0556c6d
vnode interlock to protect the knote fields [1]. The locking assumes that shared vnode lock is held, thus we get exclusive access to knote either by exclusive vnode lock protection, or by shared vnode lock + vnode interlock. Do not use kl_locked() method to assert either lock ownership or the fact that curthread does not own the lock. For shared locks, ownership is not recorded, e.g. VOP_ISLOCKED can return LK_SHARED for the shared lock not owned by curthread, causing false positives in kqueue subsystem assertions about knlist lock. Remove kl_locked method from knlist lock vector, and add two separate assertion methods kl_assert_locked and kl_assert_unlocked, that are supposed to use proper asserts. Change knlist_init accordingly. Add convenience function knlist_init_mtx to reduce number of arguments for typical knlist initialization. Submitted by: jhb [1] Noted by: jhb [2] Reviewed by: jhb Tested by: rnoland
863 lines
21 KiB
C
863 lines
21 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1989, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kdtrace.h"
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/eventhandler.h>
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#include <sys/filedesc.h>
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#include <sys/jail.h>
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#include <sys/kernel.h>
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#include <sys/kthread.h>
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#include <sys/sysctl.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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#include <sys/pioctl.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/syscall.h>
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#include <sys/vmmeter.h>
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#include <sys/vnode.h>
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#include <sys/acct.h>
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#include <sys/ktr.h>
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#include <sys/ktrace.h>
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#include <sys/unistd.h>
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#include <sys/sdt.h>
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#include <sys/sx.h>
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#include <sys/signalvar.h>
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#include <sys/vimage.h>
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#include <security/audit/audit.h>
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#include <security/mac/mac_framework.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <vm/vm_extern.h>
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#include <vm/uma.h>
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#ifdef KDTRACE_HOOKS
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#include <sys/dtrace_bsd.h>
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dtrace_fork_func_t dtrace_fasttrap_fork;
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#endif
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SDT_PROVIDER_DECLARE(proc);
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SDT_PROBE_DEFINE(proc, kernel, , create);
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SDT_PROBE_ARGTYPE(proc, kernel, , create, 0, "struct proc *");
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SDT_PROBE_ARGTYPE(proc, kernel, , create, 1, "struct proc *");
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SDT_PROBE_ARGTYPE(proc, kernel, , create, 2, "int");
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#ifndef _SYS_SYSPROTO_H_
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struct fork_args {
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int dummy;
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};
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#endif
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/* ARGSUSED */
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int
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fork(td, uap)
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struct thread *td;
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struct fork_args *uap;
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{
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int error;
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struct proc *p2;
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error = fork1(td, RFFDG | RFPROC, 0, &p2);
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if (error == 0) {
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td->td_retval[0] = p2->p_pid;
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td->td_retval[1] = 0;
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}
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return (error);
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}
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/* ARGSUSED */
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int
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vfork(td, uap)
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struct thread *td;
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struct vfork_args *uap;
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{
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int error, flags;
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struct proc *p2;
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#ifdef XEN
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flags = RFFDG | RFPROC; /* validate that this is still an issue */
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#else
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flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
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#endif
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error = fork1(td, flags, 0, &p2);
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if (error == 0) {
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td->td_retval[0] = p2->p_pid;
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td->td_retval[1] = 0;
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}
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return (error);
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}
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int
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rfork(td, uap)
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struct thread *td;
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struct rfork_args *uap;
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{
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struct proc *p2;
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int error;
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/* Don't allow kernel-only flags. */
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if ((uap->flags & RFKERNELONLY) != 0)
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return (EINVAL);
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AUDIT_ARG(fflags, uap->flags);
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error = fork1(td, uap->flags, 0, &p2);
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if (error == 0) {
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td->td_retval[0] = p2 ? p2->p_pid : 0;
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td->td_retval[1] = 0;
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}
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return (error);
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}
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int nprocs = 1; /* process 0 */
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int lastpid = 0;
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SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0,
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"Last used PID");
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/*
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* Random component to lastpid generation. We mix in a random factor to make
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* it a little harder to predict. We sanity check the modulus value to avoid
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* doing it in critical paths. Don't let it be too small or we pointlessly
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* waste randomness entropy, and don't let it be impossibly large. Using a
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* modulus that is too big causes a LOT more process table scans and slows
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* down fork processing as the pidchecked caching is defeated.
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*/
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static int randompid = 0;
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static int
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sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
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{
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int error, pid;
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error = sysctl_wire_old_buffer(req, sizeof(int));
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if (error != 0)
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return(error);
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sx_xlock(&allproc_lock);
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pid = randompid;
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error = sysctl_handle_int(oidp, &pid, 0, req);
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if (error == 0 && req->newptr != NULL) {
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if (pid < 0 || pid > PID_MAX - 100) /* out of range */
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pid = PID_MAX - 100;
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else if (pid < 2) /* NOP */
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pid = 0;
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else if (pid < 100) /* Make it reasonable */
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pid = 100;
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randompid = pid;
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}
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sx_xunlock(&allproc_lock);
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return (error);
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}
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SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW,
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0, 0, sysctl_kern_randompid, "I", "Random PID modulus");
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int
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fork1(td, flags, pages, procp)
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struct thread *td;
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int flags;
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int pages;
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struct proc **procp;
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{
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struct proc *p1, *p2, *pptr;
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struct proc *newproc;
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int ok, trypid;
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static int curfail, pidchecked = 0;
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static struct timeval lastfail;
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struct filedesc *fd;
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struct filedesc_to_leader *fdtol;
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struct thread *td2;
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struct sigacts *newsigacts;
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struct vmspace *vm2;
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int error;
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/* Can't copy and clear. */
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if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
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return (EINVAL);
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p1 = td->td_proc;
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/*
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* Here we don't create a new process, but we divorce
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* certain parts of a process from itself.
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*/
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if ((flags & RFPROC) == 0) {
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if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
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(flags & (RFCFDG | RFFDG))) {
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PROC_LOCK(p1);
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if (thread_single(SINGLE_BOUNDARY)) {
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PROC_UNLOCK(p1);
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return (ERESTART);
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}
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PROC_UNLOCK(p1);
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}
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error = vm_forkproc(td, NULL, NULL, NULL, flags);
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if (error)
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goto norfproc_fail;
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/*
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* Close all file descriptors.
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*/
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if (flags & RFCFDG) {
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struct filedesc *fdtmp;
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fdtmp = fdinit(td->td_proc->p_fd);
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fdfree(td);
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p1->p_fd = fdtmp;
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}
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/*
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* Unshare file descriptors (from parent).
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*/
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if (flags & RFFDG)
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fdunshare(p1, td);
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norfproc_fail:
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if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
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(flags & (RFCFDG | RFFDG))) {
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PROC_LOCK(p1);
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thread_single_end();
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PROC_UNLOCK(p1);
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}
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*procp = NULL;
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return (error);
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}
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/*
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* XXX
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* We did have single-threading code here
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* however it proved un-needed and caused problems
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*/
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vm2 = NULL;
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/* Allocate new proc. */
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newproc = uma_zalloc(proc_zone, M_WAITOK);
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if (TAILQ_EMPTY(&newproc->p_threads)) {
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td2 = thread_alloc();
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if (td2 == NULL) {
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error = ENOMEM;
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goto fail1;
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}
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proc_linkup(newproc, td2);
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} else
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td2 = FIRST_THREAD_IN_PROC(newproc);
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/* Allocate and switch to an alternate kstack if specified. */
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if (pages != 0) {
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if (!vm_thread_new_altkstack(td2, pages)) {
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error = ENOMEM;
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goto fail1;
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}
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}
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if ((flags & RFMEM) == 0) {
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vm2 = vmspace_fork(p1->p_vmspace);
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if (vm2 == NULL) {
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error = ENOMEM;
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goto fail1;
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}
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}
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#ifdef MAC
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mac_proc_init(newproc);
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#endif
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knlist_init_mtx(&newproc->p_klist, &newproc->p_mtx);
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STAILQ_INIT(&newproc->p_ktr);
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/* We have to lock the process tree while we look for a pid. */
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sx_slock(&proctree_lock);
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/*
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* Although process entries are dynamically created, we still keep
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* a global limit on the maximum number we will create. Don't allow
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* a nonprivileged user to use the last ten processes; don't let root
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* exceed the limit. The variable nprocs is the current number of
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* processes, maxproc is the limit.
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*/
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sx_xlock(&allproc_lock);
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if ((nprocs >= maxproc - 10 && priv_check_cred(td->td_ucred,
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PRIV_MAXPROC, 0) != 0) || nprocs >= maxproc) {
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error = EAGAIN;
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goto fail;
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}
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/*
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* Increment the count of procs running with this uid. Don't allow
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* a nonprivileged user to exceed their current limit.
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*
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* XXXRW: Can we avoid privilege here if it's not needed?
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*/
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error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0);
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if (error == 0)
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ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0);
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else {
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PROC_LOCK(p1);
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ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1,
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lim_cur(p1, RLIMIT_NPROC));
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PROC_UNLOCK(p1);
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}
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if (!ok) {
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error = EAGAIN;
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goto fail;
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}
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/*
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* Increment the nprocs resource before blocking can occur. There
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* are hard-limits as to the number of processes that can run.
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*/
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nprocs++;
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#ifdef VIMAGE
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P_TO_VPROCG(p1)->nprocs++;
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#endif
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/*
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* Find an unused process ID. We remember a range of unused IDs
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* ready to use (from lastpid+1 through pidchecked-1).
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*
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* If RFHIGHPID is set (used during system boot), do not allocate
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* low-numbered pids.
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*/
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trypid = lastpid + 1;
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if (flags & RFHIGHPID) {
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if (trypid < 10)
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trypid = 10;
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} else {
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if (randompid)
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trypid += arc4random() % randompid;
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}
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retry:
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/*
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* If the process ID prototype has wrapped around,
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* restart somewhat above 0, as the low-numbered procs
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* tend to include daemons that don't exit.
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*/
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if (trypid >= PID_MAX) {
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trypid = trypid % PID_MAX;
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if (trypid < 100)
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trypid += 100;
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pidchecked = 0;
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}
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if (trypid >= pidchecked) {
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int doingzomb = 0;
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pidchecked = PID_MAX;
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/*
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* Scan the active and zombie procs to check whether this pid
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* is in use. Remember the lowest pid that's greater
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* than trypid, so we can avoid checking for a while.
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*/
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p2 = LIST_FIRST(&allproc);
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again:
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for (; p2 != NULL; p2 = LIST_NEXT(p2, p_list)) {
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while (p2->p_pid == trypid ||
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(p2->p_pgrp != NULL &&
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(p2->p_pgrp->pg_id == trypid ||
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(p2->p_session != NULL &&
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p2->p_session->s_sid == trypid)))) {
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trypid++;
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if (trypid >= pidchecked)
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goto retry;
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}
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if (p2->p_pid > trypid && pidchecked > p2->p_pid)
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pidchecked = p2->p_pid;
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if (p2->p_pgrp != NULL) {
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if (p2->p_pgrp->pg_id > trypid &&
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pidchecked > p2->p_pgrp->pg_id)
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pidchecked = p2->p_pgrp->pg_id;
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if (p2->p_session != NULL &&
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p2->p_session->s_sid > trypid &&
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pidchecked > p2->p_session->s_sid)
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pidchecked = p2->p_session->s_sid;
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}
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}
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if (!doingzomb) {
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doingzomb = 1;
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p2 = LIST_FIRST(&zombproc);
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goto again;
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}
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}
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sx_sunlock(&proctree_lock);
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/*
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* RFHIGHPID does not mess with the lastpid counter during boot.
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*/
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if (flags & RFHIGHPID)
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pidchecked = 0;
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else
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lastpid = trypid;
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p2 = newproc;
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p2->p_state = PRS_NEW; /* protect against others */
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p2->p_pid = trypid;
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/*
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* Allow the scheduler to initialize the child.
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*/
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thread_lock(td);
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sched_fork(td, td2);
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thread_unlock(td);
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AUDIT_ARG(pid, p2->p_pid);
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LIST_INSERT_HEAD(&allproc, p2, p_list);
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LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
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PROC_LOCK(p2);
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PROC_LOCK(p1);
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sx_xunlock(&allproc_lock);
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bcopy(&p1->p_startcopy, &p2->p_startcopy,
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__rangeof(struct proc, p_startcopy, p_endcopy));
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pargs_hold(p2->p_args);
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PROC_UNLOCK(p1);
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bzero(&p2->p_startzero,
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__rangeof(struct proc, p_startzero, p_endzero));
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p2->p_ucred = crhold(td->td_ucred);
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/* Tell the prison that we exist. */
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prison_proc_hold(p2->p_ucred->cr_prison);
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PROC_UNLOCK(p2);
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/*
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|
* Malloc things while we don't hold any locks.
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|
*/
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if (flags & RFSIGSHARE)
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|
newsigacts = NULL;
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|
else
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|
newsigacts = sigacts_alloc();
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|
|
|
/*
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|
* Copy filedesc.
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|
*/
|
|
if (flags & RFCFDG) {
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fd = fdinit(p1->p_fd);
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fdtol = NULL;
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} else if (flags & RFFDG) {
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fd = fdcopy(p1->p_fd);
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fdtol = NULL;
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} else {
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fd = fdshare(p1->p_fd);
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if (p1->p_fdtol == NULL)
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p1->p_fdtol =
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filedesc_to_leader_alloc(NULL,
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NULL,
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p1->p_leader);
|
|
if ((flags & RFTHREAD) != 0) {
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|
/*
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|
* Shared file descriptor table and
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|
* shared process leaders.
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|
*/
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fdtol = p1->p_fdtol;
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FILEDESC_XLOCK(p1->p_fd);
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fdtol->fdl_refcount++;
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FILEDESC_XUNLOCK(p1->p_fd);
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} else {
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/*
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|
* Shared file descriptor table, and
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* different process leaders
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*/
|
|
fdtol = filedesc_to_leader_alloc(p1->p_fdtol,
|
|
p1->p_fd,
|
|
p2);
|
|
}
|
|
}
|
|
/*
|
|
* Make a proc table entry for the new process.
|
|
* Start by zeroing the section of proc that is zero-initialized,
|
|
* then copy the section that is copied directly from the parent.
|
|
*/
|
|
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
bzero(&td2->td_startzero,
|
|
__rangeof(struct thread, td_startzero, td_endzero));
|
|
|
|
bcopy(&td->td_startcopy, &td2->td_startcopy,
|
|
__rangeof(struct thread, td_startcopy, td_endcopy));
|
|
|
|
bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name));
|
|
td2->td_sigstk = td->td_sigstk;
|
|
td2->td_sigmask = td->td_sigmask;
|
|
td2->td_flags = TDF_INMEM;
|
|
|
|
#ifdef VIMAGE
|
|
td2->td_vnet = NULL;
|
|
td2->td_vnet_lpush = NULL;
|
|
#endif
|
|
|
|
/*
|
|
* Duplicate sub-structures as needed.
|
|
* Increase reference counts on shared objects.
|
|
*/
|
|
p2->p_flag = P_INMEM;
|
|
p2->p_swtick = ticks;
|
|
if (p1->p_flag & P_PROFIL)
|
|
startprofclock(p2);
|
|
td2->td_ucred = crhold(p2->p_ucred);
|
|
|
|
if (flags & RFSIGSHARE) {
|
|
p2->p_sigacts = sigacts_hold(p1->p_sigacts);
|
|
} else {
|
|
sigacts_copy(newsigacts, p1->p_sigacts);
|
|
p2->p_sigacts = newsigacts;
|
|
}
|
|
if (flags & RFLINUXTHPN)
|
|
p2->p_sigparent = SIGUSR1;
|
|
else
|
|
p2->p_sigparent = SIGCHLD;
|
|
|
|
p2->p_textvp = p1->p_textvp;
|
|
p2->p_fd = fd;
|
|
p2->p_fdtol = fdtol;
|
|
|
|
/*
|
|
* p_limit is copy-on-write. Bump its refcount.
|
|
*/
|
|
lim_fork(p1, p2);
|
|
|
|
pstats_fork(p1->p_stats, p2->p_stats);
|
|
|
|
PROC_UNLOCK(p1);
|
|
PROC_UNLOCK(p2);
|
|
|
|
/* Bump references to the text vnode (for procfs) */
|
|
if (p2->p_textvp)
|
|
vref(p2->p_textvp);
|
|
|
|
/*
|
|
* Set up linkage for kernel based threading.
|
|
*/
|
|
if ((flags & RFTHREAD) != 0) {
|
|
mtx_lock(&ppeers_lock);
|
|
p2->p_peers = p1->p_peers;
|
|
p1->p_peers = p2;
|
|
p2->p_leader = p1->p_leader;
|
|
mtx_unlock(&ppeers_lock);
|
|
PROC_LOCK(p1->p_leader);
|
|
if ((p1->p_leader->p_flag & P_WEXIT) != 0) {
|
|
PROC_UNLOCK(p1->p_leader);
|
|
/*
|
|
* The task leader is exiting, so process p1 is
|
|
* going to be killed shortly. Since p1 obviously
|
|
* isn't dead yet, we know that the leader is either
|
|
* sending SIGKILL's to all the processes in this
|
|
* task or is sleeping waiting for all the peers to
|
|
* exit. We let p1 complete the fork, but we need
|
|
* to go ahead and kill the new process p2 since
|
|
* the task leader may not get a chance to send
|
|
* SIGKILL to it. We leave it on the list so that
|
|
* the task leader will wait for this new process
|
|
* to commit suicide.
|
|
*/
|
|
PROC_LOCK(p2);
|
|
psignal(p2, SIGKILL);
|
|
PROC_UNLOCK(p2);
|
|
} else
|
|
PROC_UNLOCK(p1->p_leader);
|
|
} else {
|
|
p2->p_peers = NULL;
|
|
p2->p_leader = p2;
|
|
}
|
|
|
|
sx_xlock(&proctree_lock);
|
|
PGRP_LOCK(p1->p_pgrp);
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
/*
|
|
* Preserve some more flags in subprocess. P_PROFIL has already
|
|
* been preserved.
|
|
*/
|
|
p2->p_flag |= p1->p_flag & P_SUGID;
|
|
td2->td_pflags |= td->td_pflags & TDP_ALTSTACK;
|
|
SESS_LOCK(p1->p_session);
|
|
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
|
|
p2->p_flag |= P_CONTROLT;
|
|
SESS_UNLOCK(p1->p_session);
|
|
if (flags & RFPPWAIT)
|
|
p2->p_flag |= P_PPWAIT;
|
|
|
|
p2->p_pgrp = p1->p_pgrp;
|
|
LIST_INSERT_AFTER(p1, p2, p_pglist);
|
|
PGRP_UNLOCK(p1->p_pgrp);
|
|
LIST_INIT(&p2->p_children);
|
|
|
|
callout_init(&p2->p_itcallout, CALLOUT_MPSAFE);
|
|
|
|
#ifdef KTRACE
|
|
/*
|
|
* Copy traceflag and tracefile if enabled.
|
|
*/
|
|
mtx_lock(&ktrace_mtx);
|
|
KASSERT(p2->p_tracevp == NULL, ("new process has a ktrace vnode"));
|
|
if (p1->p_traceflag & KTRFAC_INHERIT) {
|
|
p2->p_traceflag = p1->p_traceflag;
|
|
if ((p2->p_tracevp = p1->p_tracevp) != NULL) {
|
|
VREF(p2->p_tracevp);
|
|
KASSERT(p1->p_tracecred != NULL,
|
|
("ktrace vnode with no cred"));
|
|
p2->p_tracecred = crhold(p1->p_tracecred);
|
|
}
|
|
}
|
|
mtx_unlock(&ktrace_mtx);
|
|
#endif
|
|
|
|
/*
|
|
* If PF_FORK is set, the child process inherits the
|
|
* procfs ioctl flags from its parent.
|
|
*/
|
|
if (p1->p_pfsflags & PF_FORK) {
|
|
p2->p_stops = p1->p_stops;
|
|
p2->p_pfsflags = p1->p_pfsflags;
|
|
}
|
|
|
|
#ifdef KDTRACE_HOOKS
|
|
/*
|
|
* Tell the DTrace fasttrap provider about the new process
|
|
* if it has registered an interest.
|
|
*/
|
|
if (dtrace_fasttrap_fork)
|
|
dtrace_fasttrap_fork(p1, p2);
|
|
#endif
|
|
|
|
/*
|
|
* This begins the section where we must prevent the parent
|
|
* from being swapped.
|
|
*/
|
|
_PHOLD(p1);
|
|
PROC_UNLOCK(p1);
|
|
|
|
/*
|
|
* Attach the new process to its parent.
|
|
*
|
|
* If RFNOWAIT is set, the newly created process becomes a child
|
|
* of init. This effectively disassociates the child from the
|
|
* parent.
|
|
*/
|
|
if (flags & RFNOWAIT)
|
|
pptr = initproc;
|
|
else
|
|
pptr = p1;
|
|
p2->p_pptr = pptr;
|
|
LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
|
|
sx_xunlock(&proctree_lock);
|
|
|
|
/* Inform accounting that we have forked. */
|
|
p2->p_acflag = AFORK;
|
|
PROC_UNLOCK(p2);
|
|
|
|
/*
|
|
* Finish creating the child process. It will return via a different
|
|
* execution path later. (ie: directly into user mode)
|
|
*/
|
|
vm_forkproc(td, p2, td2, vm2, flags);
|
|
|
|
if (flags == (RFFDG | RFPROC)) {
|
|
PCPU_INC(cnt.v_forks);
|
|
PCPU_ADD(cnt.v_forkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
|
|
PCPU_INC(cnt.v_vforks);
|
|
PCPU_ADD(cnt.v_vforkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else if (p1 == &proc0) {
|
|
PCPU_INC(cnt.v_kthreads);
|
|
PCPU_ADD(cnt.v_kthreadpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else {
|
|
PCPU_INC(cnt.v_rforks);
|
|
PCPU_ADD(cnt.v_rforkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
}
|
|
|
|
/*
|
|
* Both processes are set up, now check if any loadable modules want
|
|
* to adjust anything.
|
|
* What if they have an error? XXX
|
|
*/
|
|
EVENTHANDLER_INVOKE(process_fork, p1, p2, flags);
|
|
|
|
/*
|
|
* Set the child start time and mark the process as being complete.
|
|
*/
|
|
microuptime(&p2->p_stats->p_start);
|
|
PROC_SLOCK(p2);
|
|
p2->p_state = PRS_NORMAL;
|
|
PROC_SUNLOCK(p2);
|
|
|
|
/*
|
|
* If RFSTOPPED not requested, make child runnable and add to
|
|
* run queue.
|
|
*/
|
|
if ((flags & RFSTOPPED) == 0) {
|
|
thread_lock(td2);
|
|
TD_SET_CAN_RUN(td2);
|
|
sched_add(td2, SRQ_BORING);
|
|
thread_unlock(td2);
|
|
}
|
|
|
|
/*
|
|
* Now can be swapped.
|
|
*/
|
|
PROC_LOCK(p1);
|
|
_PRELE(p1);
|
|
PROC_UNLOCK(p1);
|
|
|
|
/*
|
|
* Tell any interested parties about the new process.
|
|
*/
|
|
knote_fork(&p1->p_klist, p2->p_pid);
|
|
SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0);
|
|
|
|
/*
|
|
* Preserve synchronization semantics of vfork. If waiting for
|
|
* child to exec or exit, set P_PPWAIT on child, and sleep on our
|
|
* proc (in case of exit).
|
|
*/
|
|
PROC_LOCK(p2);
|
|
while (p2->p_flag & P_PPWAIT)
|
|
cv_wait(&p2->p_pwait, &p2->p_mtx);
|
|
PROC_UNLOCK(p2);
|
|
|
|
/*
|
|
* Return child proc pointer to parent.
|
|
*/
|
|
*procp = p2;
|
|
return (0);
|
|
fail:
|
|
sx_sunlock(&proctree_lock);
|
|
if (ppsratecheck(&lastfail, &curfail, 1))
|
|
printf("maxproc limit exceeded by uid %i, please see tuning(7) and login.conf(5).\n",
|
|
td->td_ucred->cr_ruid);
|
|
sx_xunlock(&allproc_lock);
|
|
#ifdef MAC
|
|
mac_proc_destroy(newproc);
|
|
#endif
|
|
fail1:
|
|
if (vm2 != NULL)
|
|
vmspace_free(vm2);
|
|
uma_zfree(proc_zone, newproc);
|
|
pause("fork", hz / 2);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Handle the return of a child process from fork1(). This function
|
|
* is called from the MD fork_trampoline() entry point.
|
|
*/
|
|
void
|
|
fork_exit(callout, arg, frame)
|
|
void (*callout)(void *, struct trapframe *);
|
|
void *arg;
|
|
struct trapframe *frame;
|
|
{
|
|
struct proc *p;
|
|
struct thread *td;
|
|
struct thread *dtd;
|
|
|
|
td = curthread;
|
|
p = td->td_proc;
|
|
KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new"));
|
|
|
|
CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)",
|
|
td, td->td_sched, p->p_pid, td->td_name);
|
|
|
|
sched_fork_exit(td);
|
|
/*
|
|
* Processes normally resume in mi_switch() after being
|
|
* cpu_switch()'ed to, but when children start up they arrive here
|
|
* instead, so we must do much the same things as mi_switch() would.
|
|
*/
|
|
if ((dtd = PCPU_GET(deadthread))) {
|
|
PCPU_SET(deadthread, NULL);
|
|
thread_stash(dtd);
|
|
}
|
|
thread_unlock(td);
|
|
|
|
/*
|
|
* cpu_set_fork_handler intercepts this function call to
|
|
* have this call a non-return function to stay in kernel mode.
|
|
* initproc has its own fork handler, but it does return.
|
|
*/
|
|
KASSERT(callout != NULL, ("NULL callout in fork_exit"));
|
|
callout(arg, frame);
|
|
|
|
/*
|
|
* Check if a kernel thread misbehaved and returned from its main
|
|
* function.
|
|
*/
|
|
if (p->p_flag & P_KTHREAD) {
|
|
printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n",
|
|
td->td_name, p->p_pid);
|
|
kproc_exit(0);
|
|
}
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
|
|
EVENTHANDLER_INVOKE(schedtail, p);
|
|
}
|
|
|
|
/*
|
|
* Simplified back end of syscall(), used when returning from fork()
|
|
* directly into user mode. Giant is not held on entry, and must not
|
|
* be held on return. This function is passed in to fork_exit() as the
|
|
* first parameter and is called when returning to a new userland process.
|
|
*/
|
|
void
|
|
fork_return(td, frame)
|
|
struct thread *td;
|
|
struct trapframe *frame;
|
|
{
|
|
|
|
userret(td, frame);
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_SYSRET))
|
|
ktrsysret(SYS_fork, 0, 0);
|
|
#endif
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
}
|